If you eat canned tuna, you should choose light rather than white tuna, according to the latest tests for toxic mercury by Consumer Reports.
Of 42 samples taken from cans and pouches of tuna in the New York area, all every single sample was contaminated with mercury, a toxic element that is found in fish because pollution from coal-fired industry and power production rains down into the oceans, contaminating the food that tuna and other predatory fish eat. (Rates of mercury contamination in Pacific fish have been increasing.) Because tuna is contaminated, and is consumed more than any other fish in the U.S., it is the top source of mercury exposure in America. Mercury can permanently damage the brain, so exposure is particularly a concern for pregnant women, women who may become pregnant (because the body doesn't rid itself of mercury immediately), and young children particularly those under the age of six, who weigh less than 45 pounds.
While the Food and Drug Administration and the Environmental Protection Agency have recognized the threat posed by consuming canned tuna, the recommendations for limiting consumption are too weak, according to Consumer's Union, the publisher of Consumer Reports. The FDA recommends that women who are or may become pregnant, women who are nursing and young children limit their tuna consumption to 12 ounces of light tuna (about two servings) or 6 ounces of white tuna (about one serving) per week.
Consumers Union advises pregnant women, to avoid exposure the EPA considers dangerous, to avoid eating tuna altogether. According to its latest tests, pregnant woman who eats half a can of white tuna would exceed the safe exposure limit in every case, and a pregnant woman eating one can of light tuna would exceed the safe exposure limit half the time. Consumer's Union recommends that children limit their consumption as follows:
Children who weigh more than 45 pounds: No more than 12.5 ounces of light tuna, or 4 ounces of white tuna per week.
Children who weigh less than 45 pounds: No more than 4 ounces of light tuna, or 1.5 ounces of white tuna.
The latest round of testing showed again how light and white tuna have vastly different contamination levels. The light tuna sample with the most mercury still had less than the white tuna sample with the least mercury. Past testing by Consumer Reports, however, has demonstrated that some cans of light tuna (as much as 6%) had as much mercury as the average can of white tuna.
Other fish high in mercury include shark, swordfish, king mackerel and tilefish.
Not all fish are contaminated to the same degree, however, and fish can also be rich in protein, Vitamin D, and omega-3 fatty acids. Low-mercury fish include clams, wild Alaskan salmon, shrimp, tilapia, oysters, pollock, sardines, Pacific flounder and sole, herring, mullet, and scallops. To find fish that are low in contaminants, high in nutrients and that are fished sustainably, use Environmental Defense Fund's Seafood Selector.
Also, when buying tuna, look for dolphin-safe tuna from StarKist (Del Monte), Chicken of the Sea (ThaiUnion Int.) or BumbleBee each of which is certified by the Earth Island Institute.
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